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      1 //===-- CodeGen/AsmPrinter/Win64Exception.cpp - Dwarf Exception Impl ------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file contains support for writing Win64 exception info into asm files.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "DwarfException.h"
     15 #include "llvm/ADT/SmallString.h"
     16 #include "llvm/ADT/StringExtras.h"
     17 #include "llvm/ADT/Twine.h"
     18 #include "llvm/CodeGen/AsmPrinter.h"
     19 #include "llvm/CodeGen/MachineFrameInfo.h"
     20 #include "llvm/CodeGen/MachineFunction.h"
     21 #include "llvm/CodeGen/MachineModuleInfo.h"
     22 #include "llvm/IR/DataLayout.h"
     23 #include "llvm/IR/Mangler.h"
     24 #include "llvm/IR/Module.h"
     25 #include "llvm/MC/MCAsmInfo.h"
     26 #include "llvm/MC/MCContext.h"
     27 #include "llvm/MC/MCExpr.h"
     28 #include "llvm/MC/MCSection.h"
     29 #include "llvm/MC/MCStreamer.h"
     30 #include "llvm/MC/MCSymbol.h"
     31 #include "llvm/Support/Dwarf.h"
     32 #include "llvm/Support/ErrorHandling.h"
     33 #include "llvm/Support/FormattedStream.h"
     34 #include "llvm/Target/TargetFrameLowering.h"
     35 #include "llvm/Target/TargetLoweringObjectFile.h"
     36 #include "llvm/Target/TargetOptions.h"
     37 #include "llvm/Target/TargetRegisterInfo.h"
     38 using namespace llvm;
     39 
     40 Win64Exception::Win64Exception(AsmPrinter *A)
     41   : EHStreamer(A), shouldEmitPersonality(false), shouldEmitLSDA(false),
     42     shouldEmitMoves(false) {}
     43 
     44 Win64Exception::~Win64Exception() {}
     45 
     46 /// endModule - Emit all exception information that should come after the
     47 /// content.
     48 void Win64Exception::endModule() {
     49 }
     50 
     51 /// beginFunction - Gather pre-function exception information. Assumes it's
     52 /// being emitted immediately after the function entry point.
     53 void Win64Exception::beginFunction(const MachineFunction *MF) {
     54   shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
     55 
     56   // If any landing pads survive, we need an EH table.
     57   bool hasLandingPads = !MMI->getLandingPads().empty();
     58 
     59   shouldEmitMoves = Asm->needsSEHMoves();
     60 
     61   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
     62   unsigned PerEncoding = TLOF.getPersonalityEncoding();
     63   const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
     64 
     65   shouldEmitPersonality = hasLandingPads &&
     66     PerEncoding != dwarf::DW_EH_PE_omit && Per;
     67 
     68   unsigned LSDAEncoding = TLOF.getLSDAEncoding();
     69   shouldEmitLSDA = shouldEmitPersonality &&
     70     LSDAEncoding != dwarf::DW_EH_PE_omit;
     71 
     72   if (!shouldEmitPersonality && !shouldEmitMoves)
     73     return;
     74 
     75   Asm->OutStreamer.EmitWinCFIStartProc(Asm->CurrentFnSym);
     76 
     77   if (!shouldEmitPersonality)
     78     return;
     79 
     80   const MCSymbol *PersHandlerSym =
     81       TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
     82   Asm->OutStreamer.EmitWinEHHandler(PersHandlerSym, true, true);
     83 
     84   Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
     85                                                 Asm->getFunctionNumber()));
     86 }
     87 
     88 /// endFunction - Gather and emit post-function exception information.
     89 ///
     90 void Win64Exception::endFunction(const MachineFunction *) {
     91   if (!shouldEmitPersonality && !shouldEmitMoves)
     92     return;
     93 
     94   Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
     95                                                 Asm->getFunctionNumber()));
     96 
     97   // Map all labels and get rid of any dead landing pads.
     98   MMI->TidyLandingPads();
     99 
    100   if (shouldEmitPersonality) {
    101     Asm->OutStreamer.PushSection();
    102     Asm->OutStreamer.EmitWinEHHandlerData();
    103     emitExceptionTable();
    104     Asm->OutStreamer.PopSection();
    105   }
    106   Asm->OutStreamer.EmitWinCFIEndProc();
    107 }
    108